A productive, veteran NHL center, Ribeiro first made his mark in the Quebec Major Junior Hockey League with Rouyn-Noranda. In 1997-98 he won the Michel Bergeron Trophy as the QMJHL's top rookie and the Paul Dumont Trophy as its personality of the year after leading the league in assists (85). He was named to the 1998 Canadian Hockey League All-Rookie Team and QMJHL Second All-Star Team and played in the 1998 CHL Top Prospects Game.

The Montreal Canadiens selected Ribeiro in the second round (No. 45) of the 1998 NHL Draft. In 1998-99 he was named a CHL First-Team All-Star and QMJHL First-Team All-Star after claiming the CHL Top Scorer Award and the Jean Beliveau Trophy for most points in the QMJHL with 167 (67 goals).

He made his NHL debut for Montreal on Oct. 2, 1999, against the Toronto Maple Leafs and scored his first NHL goal Oct. 23, 1999, also against Toronto. Ribeiro helped Canada win a bronze medal at the 2000 World Junior Championship.

He led Quebec of the American Hockey League with 66 points in 2000-01 and had four points in the 2002 YoungStars Game. After starting the 2002-03 season with Hamilton of the AHL, Ribeiro was called up to Montreal in November. He spent the rest of the season with the Canadiens and in 2003-04 led them in assists (45) and points (65).

On Sept. 30, 2006, Ribeiro was traded to the Dallas Stars along with a 2008 sixth-round draft pick for Janne Niinimaa and a 2007 fifth-round pick. Ribeiro led the Stars with 59 points in 2006-07, also led them in that category in the 2007-08 regular season (83) and playoffs (17) and again was Dallas' top scorer in 2008-09 (78 points). He also led the Stars with 56 assists in 2007-08 and 52 assists in 2010-11.

On June 22, 2012, the Stars traded Ribeiro to the Washington Capitals for Cody Eakin and a 2012 second-round draft pick. In 2012-13 he led the NHL in power-play assists (21) and shared the league lead in power-play points (27) with teammate Alex Ovechkin.

After signing as a free agent with the then-Phoenix Coyotes on July 5, 2013, he was tied for third on the team in assists (31) and tied for fourth in points (47) in 2013-14.

The Nashville Predators signed Ribeiro as a free agent July 15, 2014. He had 62 points in 2014-15 and set a franchise record for assists by a center (47). Ribeiro played his 1,000th NHL game Feb. 6, 2016, against the San Jose Sharks.